Source : WordNet®

alpha receptor
     n : receptors postulated to exist on nerve cell membranes of the
         sympathetic nervous system in order to explain the
         specificity of certain agents that affect only some
         sympathetic activities (such as vasoconstriction and
         relaxation of intestinal muscles and contraction of
         smooth muscles) [syn: {alpha-adrenergic receptor}, {alpha-adrenoceptor}]